Contact lenses work by sitting atop the cornea and compensating for its flaws to achieve focus on the retina. LASIK permanently sculpts the cornea into the proper shape. "We use a machine to lift a thin membrane, or flap, which is a tenth-of-a-millimeter thick," Moadel explains. "We then just lift the flap and use the laser to reshape the surface underneath by a few thousandths of a millimeter. Then we simply put this flap back, moisten it, and it seals in place by itself, within a 12 to 24 hour period."
During office visits before the day of surgery, Moadel makes precise measurements of a patient's eyes, and feeds that information into a computer to determine how much corneal material to remove. "We actually measure patients two to three times for consistency," he says.
Once a flap in one eye has been peeled back, Moadel is ready to use the excimer laser, which destroys corneal material with ultraviolet light. "The laser is not burning, it's not heat," Moadel explains. "It's basically vaporizing. Every pulse of that laser removes a quarter-micron of cornea." In cases of myopia, microthin layers of cornea are eliminated to flatten its shape.
For hyperopia, a doughnut-shaped hole is made to create a more conical shape. On average, the laser procedure itself takes less than two minutes per eye. When it's done, patients spend a half-hour resting in a darkened lounge, then following one more examination, they're free to go home.